The present invention relates to watercraft, and in particular to a personal watercraft that is powered solely by its occupants.
A variety of personal watercraft exist that allow individuals to propel themselves across the surface of a body of water. Traditionally, personal watercraft were designed to move as a person sits reclined or lies prone and turns pedals with the hands and/or feet. These pedals are connected to a propeller by any one of a number of standard mechanical transmission systems. The propellers would typically spin below the surface of the water, though occasionally a watercraft would have a propeller that spins above and behind the craft, providing forward thrust by pushing air.
The primary drawback of these vehicles has always been the relatively low speed at which they may operate in comparison to motorized watercraft. This limitation results from the fact that fluid resistance to the watercraft""s motion increases proportionally with respect to the square of the speed, and the capability of a human occupant to provide the power necessary to overcome that resistance is severely limited.
Initial efforts to overcome speed limitations sought to improve the efficiency of the power transmission system by which the energy expended by the occupant propelled water. In this vein, complex pulley and gear schemes were developed, as exemplified by Rybczyk, U.S. Pat. No. 5,090,928 and Harris, U.S. Pat. No. 5,368,507. In some instances, as seen by Kindred, U.S. Pat. No. 4,172,427 and Han, U.S. Pat. No. 6,033,276, fins were substituted for propellers in order to simulate the movement of fish through water. Regardless, such designs were always constrained by the limited power available from a human occupant.
An alternate approach sought to reduce the resistance, or drag, that the surrounding water imparted to the craft. In this regard, a number of lightweight personal watercraft were designed with improved hydrodynamic characteristics. One such design, exemplified by Hoffman, U.S. Pat. No. 4,349,340, mounted hydrofoils to the body of the watercraft so that the craft""s hull was raised from the water when it reached a certain speed. Once raised from the water, the only drag force imparted to the craft resulted from the foils. Unfortunately, even this design is limited in that the weight of the occupant bears down on the watercraft, which must be raised above the surface of the water, impeding forward motion. More importantly, this watercraft requires a substantial expenditure of energy which can only be achieved by an occupant for a short period of time.
What is desired, then, is a personal watercraft that addresses the aforementioned shortcomings by providing an efficient propulsion mechanism to transfer the occupant""s expended energy into forward motion, by reducing the drag that water imparts to the watercraft, and by minimizing the occupant""s weight that bears on the watercraft.
The present invention addresses the aforementioned shortcomings by providing a watercraft that includes at least one stepper. Each stepper is pivotally associated with a propulsion member that is moveable in a generally vertical direction so that the propulsion member is in a first position during downward motion of the stepper and a second position during upward motion of the stepper.
In one aspect, the invention provides for at least one floatation member and at least one stepper. Each stepper is pivotally associated with a propulsion member moveable in a generally vertical direction so that the propulsion member is in a first position during downward motion of the stepper and a second position during upward motion of the stepper.
Another aspect of the invention provides for at least one floatation member and at least one moveable member operable by a person. This moveable member operates at least one propulsion member suitable to cause the watercraft to move in a first direction where said person is substantially supported by the propulsion member and is substantially free from being supported by the floatation member.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the preferred embodiment of the invention, taken in conjunction with the accompanying drawings.